Lacrimal apparatus: Lacrimal gland, Lacrimal canaliculi, Lacrimal sac, Nasolacrimal duct

June 12, 2012 | By | Reply More

Lacrimal apparatus: Lacrimal gland, Lacrimal canaliculi, Lacrimal sac, Nasolacrimal duct

Lacrimal apparatus:

  • A system containing the orbital structures for tear production and drainage.
  • Consists of:
  1. Lacrimal gland
  2. Lacrimal canaliculi
  3. Lacrimal sac
  4. Nasolacrimal duct

1.Lacrimal gland

  • Paired almond-shaped glands, one for each eye
  • Secretes the aqueous layer of the tear film.
  • Situated in the upper, outer portion of each orbit.
  • It is lodged in the lacrimal fossa of the orbit formed by the frontal bone.
  • Has palpebral portion and orbital portion
  • Palpebral portion lies close to the eye.
  • Orbital portion contains fine interlobular ducts that unite to form 3 – 5 main excretory ducts, joining 5 – 7 ducts in the palpebral portion before the secreted fluid may enter on the surface of the eye.

2.Lacrimal puncta and canaliculi

  • There are two lacrimal puncta in the medial (inside) portion of each eye.
  • Collect tears and conveys to lacrimal sac through lacrimal canaliculi.
  • Lacrimal canaliculi are small channels in each eyelid that commence at lacrimal puncta.
  • superior duct, the smaller and shorter of the two, at first ascends, and then bends at an acute angle, and passes medialward and downward to the lacrimal sac.
  • inferior duct at first descends, and then runs almost horizontally to the lacrimal sac.
  • At the angles they are dilated into ampullæ

3.Lacrimal sac

  • Lacrimal sac is the upper dilated end of the nasolacrimal duct
  • Lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla.
  • It connects the lacrimal canaliculi, which drain tears from the eye’s surface, and the nasolacrimal duct, which conveys this fluid into the nasal cavity.
  • oval in form
  • measures from 12 to 15 mm. in length
  • upper end is closed and rounded
  • lower end is continued into the nasolacrimal duct.

4.Nasolacrimal duct

  • Carries tears from the lacrimal sac into the nasal cavity. Excess tears flow through nasolacrimal duct which drains into the inferior nasal meatus.
  • Duct is lined by stratified columnar epithelium containing mucus-secreting goblet cells, and is surrounded by connective tissue.
  • Obstruction of the nasolacrimal duct leads to the excess overflow of tears called epiphora


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Category: Anatomy, Medical

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